Two questions, really.
There have been a number of "extinction events" on Earth, where countless numbers of different species have been wiped out in a very short time. The best-known of these is the K-T extinction, which put an end to the dinosaurs and many other species (mainly in the Northern Hemisphere, for reasons we do not understand). It is generally believed that this event was caused by an large meteor or comet striking the Earth on the Yucatan peninsula in what is now Mexico. Other extinction events have been caused by global cooling and (probably) supervolcano eruptions. (More about the latter in a moment).
What is the end of the world? Another extinction event? Will it be when mankind does something REALLY stupid and puts an end to itself?
If you wait long enough the Earth will be consumed by the Sun when it enters its red giant phase, is that the sort of end you mean?
Forward projections suggest that gravitational interaction between Mars and Venus will result in one of them being thrown out of orbit billions of years in the future. Since Earth is between them, orbitally speaking, it will almost certainly be affected badly, - another sort of end?
Back to the supervolcanoes. Yellowstone Park is on the top of one of the largest supervolcanoes on earth. Geological evidence suggests that it erupts around every 600,000 years. It last erupted 650,000 years ago.
Yellowstone is overdue.
We believe that the last time it erupted it covered most of what is America from the Pacific coast, past the midwest with ash, sometimes many metres deep. Much of this area is called "the breadbasket of the World". The world would starve for centuries.
And on that cheery note - don't have nightmares - most of this is so far in the future (Yellowstone could still be another 200,000 years coming) that you can sleep well tonight.
